Performing a non-disruptive software upgrade on physical storage processors having access to virtual storage processors

ABSTRACT

A non-disruptive upgrade technique involves, with (i) a first SP using first virtual SPs (VSPs) defining first environments for first host file systems, (ii) a second SP using second VSPs defining second environments for second host file systems, and (iii) an initial software version installed on each SP, processing host I/Os on the host file systems by the SPs. The technique further involves moving the first VSPs from the first SP to the second SP to provision the second SP to process host I/Os concurrently on the first and second host file systems using the first and second VSPs. The technique further involves, after moving the first VSPs from the first SP to the second SP and while the second SP processes host I/Os concurrently on the first and second host file systems using the first and second VSPs, installing a new backwards compatible software version on the first SP.

BACKGROUND

Data storage systems typically include one or more physical storageprocessors (SPs) accessing an array of disk drives and/or electronicflash drives. Each SP is connected to a network, such as the Internetand/or a storage area network (SAN), and receives transmissions over thenetwork from host computing devices (“hosts”). The transmissions fromthe hosts include “IO requests,” also called “host IOs.” Some IOrequests direct the SP to read data from an array, whereas other IOrequests direct the SP to write data to the array. Also, some IOrequests perform block-based data requests, where data are specified byLUN (Logical Unit Number) and offset values, whereas others performfile-based requests, where data are specified using file names andpaths. Block-based IO requests typically conform to a block-basedprotocol, such as Fibre Channel or iSCSI (Internet SCSI, where SCSI isan acronym for Small Computer System Interface), for example. File-basedIO requests typically conform to a file-based protocol, such as NFS(Network File System), CIFS (Common Internet File System), or SMB(Server Message Block), for example.

In some data storage systems, an SP may operate one or more virtual datamovers. As is known, a virtual data mover is a logical grouping of filesystems and servers that is managed by the SP and provides a separatecontext for managing host data stored on the array. A single SP mayprovide multiple virtual data movers for different users or groups. Forexample, a first virtual data mover may organize data for users in afirst department of a company, whereas a second virtual data mover mayorganize data for users in a second department of the company. Eachvirtual data mover may include any number of host file systems forstoring user data.

SUMMARY

In a typical virtual data mover arrangement, the SP has a root filesystem with mount points to which the host file systems of each virtualdata mover are mounted. Thus, the SP and all its virtual data moversform a single, large directory and all share a common namespace. Hostscan access their virtual data mover-managed data by connecting to the SPover the network, logging on, and specifying paths relative to the SP'sroot where their data are kept. The typical arrangement thus requireshosts to access data of a virtual data mover using paths that arereferenced to and dependent upon the root of the SP.

In addition, settings for prescribing virtual data mover operations areconventionally stored in the root file system of the SP. Many of thesesettings are global to all virtual data movers operating on the SP;others may be specific to particular virtual data movers.

Unfortunately, the intermingling of virtual data mover content within anSP's root file system impairs the ease of mobility and management ofvirtual data movers. For example, administrators wishing to move avirtual data mover (e.g., its file systems, settings, and servers) fromone SP to another SP must typically perform many steps on a varietydifferent data objects. File systems, server configurations, and othersettings may need to be moved one at a time. Also, as the contents ofdifferent virtual data movers are often co-located, care must be takento ensure that changes affecting one virtual data mover do not disruptthe operation of other virtual data movers. Moreover, to perform anon-disruptive software upgrade on the data storage system, it may makesense to move a conventional virtual data mover from one physical SP toanother, but the above-described complexity of conventional virtual datamovers makes it prohibitively difficult to move a conventional virtualdata mover among physical SPs.

In contrast to the above-described conventional virtual data moverswhich are not moved among physical SPs due to their complexity, improvedtechniques are directed to performing a non-disruptive upgrade (NDU) ofsoftware on a data storage apparatus having multiple physical SPs whichaccess virtual storage processors (VSPs). The VSPs are capable of beingmoved from one physical SP to another during NDU. Accordingly, a newversion of software can be installed on each physical SP while thatphysical SP is free of VSPs, i.e., with the VSPs residing on one or moreremaining physical SPs of the data storage apparatus. Additionally, thenew version of the software is capable of being backwards compatible sothat once all of the physical SPs have the new version installed, acoordinated switchover can take place which commits the data storageapparatus to operating in accordance with a new mode that is differentfrom the backwards compatible mode.

One embodiment is directed to a method of performing a non-disruptiveupgrade of software installed on physical storage processors of a datastorage apparatus. The method includes, with (i) a first physicalstorage processor initially using a first set of virtual storageprocessors (VSPs) to define a first set of operating environments for afirst set of host file systems, (ii) a second physical storage processorinitially using a second set of VSPs to define a second set of operatingenvironments for a second set of host file systems, and (iii) an initialversion of the software being installed on each of the first and secondphysical storage processors, processing host input/output (I/O) requestson the host file systems by the physical storage processors. The methodfurther includes moving the first set of VSPs from the first physicalstorage processor to the second physical storage processor to provisionthe second physical storage processor to process host I/O requestsconcurrently on the first and second sets of host file systems using thefirst and second sets of VSPs. The method further includes, after thefirst set of VSPs is moved from the first physical storage processor tothe second physical storage processor and while the second physicalstorage processor processes host I/O requests concurrently on the firstand second sets of host file systems using the first and second sets ofVSPs, installing a new version of the software on the first physicalstorage processor, the new version of the software being backwardscompatible with the initial version of the software.

In some arrangements, the method further includes, after the new versionof the software is installed on the first physical storage processor,moving the first and second sets of VSPs from the second physicalstorage processor to the first physical storage processor to provisionthe first physical storage processor to process host I/O requestsconcurrently on the first and second sets of host file systems using thefirst and second sets of VSPs. In these arrangements, the method furtherincludes, after the first and second sets of VSPs are moved from thesecond physical storage processor to the first physical storageprocessor and while the first physical storage processor processes hostI/O requests concurrently on the first and second sets of host filesystems using the first and second sets of VSPs, installing the newversion of the software on the second physical storage processor.

In some arrangements, the method further includes, moving the second setof VSPs from the first physical storage processor back to the secondphysical storage processor to re-provision the second physical storageprocessor to process host I/O requests on the second set of host filesystems using the second set of VSPs. The method further includes, afterthe second set of VSPs is moved from the first physical storageprocessor back to the second physical storage processor, processing hostI/O requests on the host file systems by the physical storage processorswhile the new version of the software is installed on the physicalstorage processors.

In some arrangements, processing host I/O requests on the host filesystems by the physical storage processors while the new version of thesoftware is installed on the physical storage processors includesprocessing host I/O requests on the host file systems by the physicalstorage processors while each of the first and second physical storageprocessors operates using the new version of the software in a backwardcompatible mode. Accordingly, the host I/O requests are processed in thesame manner as that of the initial version of the software.

In some arrangements, the method further includes receiving a commitcommand and, in response to the commit command, switching each of thefirst and second physical storage processors from operating using thenew version of the software in the backward compatible mode to operatingusing the new version of the software in a new version mode which isdifferent than the backward compatible mode. Such a command may beprovided by a user through a user interface for user control overcommitment.

In some arrangements, operating the first and second physical storageprocessors using the new version of the software in the backwardcompatible mode includes processing host I/O requests in accordance witha first file-based protocol. In these arrangements, operating the firstand second physical storage processors using the new version of thesoftware in the new version mode may include processing host I/Orequests in accordance with a second file-based protocol that isdifferent than the first file-based protocol.

In some arrangements, the method further includes receiving a completioncommand and, in response to the completion command, deeming thenon-disruptive upgrade of the software to be complete while continuingto operate each of the first and second physical storage processorsusing the new version of the software in the backward compatible moderather than switch to using the new version of the software in a newversion mode which is different than the backward compatible mode. Sucharrangements, allow NDU to be viewed as completed even though commitmentmay be deferred for an extended period of time.

In some arrangements, wherein each VSP includes a root file system and aVSP configuration file system contained within a set of lower-deck fileof a lower-deck file system of the data storage apparatus, the VSPconfiguration file system storing VSP data which identifies host filesystem operating environment characteristics. In these arrangements,using the first set of VSPs to define the first set of operatingenvironments includes accessing the VSP configuration file system ofeach VSP of the first set. Additionally, using the second set of VSPs todefine the second set of operating environments includes accessing theVSP configuration file system of each VSP of the second set.

In some arrangements, the data storage apparatus includes at least twophysical storage processors. In these arrangements, the method mayfurther include, prior to processing the host I/O requests on the hostfile systems by the physical storage processors, updating aconfiguration database to identify, for each VSP, one of the physicalstorage processors as a primary owner of that VSP. Each VSP resides onits primary owner upon completion of the non-disruptive upgrade.

In some arrangements, the method further includes trespassingblock-based processing among the physical storage processors in tandemwith moving VSPs among the physical storage processors to removeprocessing of all host I/O requests from each physical storage processorwhen the new version of the software is installed on that physicalstorage processor. Accordingly, NDU can be performed on a data storageapparatus having physical SPs which process both file-based andblock-based host I/O requests.

It should be understood that, in the cloud context, processing circuitryis formed by remote computer resources distributed over a network. Sucha computing environment is capable of providing certain advantages suchas enhanced fault tolerance, load balancing, processing flexibility,etc.

Other embodiments are directed to electronic systems and apparatus,processing circuits, computer program products, and so on. Someembodiments are directed to various methods, electronic components andcircuitry which are involved in performing a non-disruptive upgrade ofsoftware installed on physical storage processors of a data storageapparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages will be apparent fromthe following description of particular embodiments of the invention, asillustrated in the accompanying drawings, in which like referencecharacters refer to the same parts throughout the different views. Inthe accompanying drawings,

FIG. 1 is a block diagram showing an example data storage apparatus inan environment wherein improved techniques hereof may be practiced, thedata storage apparatus including a storage processor having multiplevirtualized storage processors (VSPs);

FIG. 2 is a block diagram showing example features of the front end ofFIG. 1 in additional detail;

FIG. 3 is a block diagram showing an example set of file systems of aVSP of FIG. 1;

FIG. 4 is a table showing an example set of records stored in aconfiguration database that defines a VSP that can be run on the storageprocessor of FIG. 1;

FIGS. 5A and 5B are block diagrams showing example arrangements ofvirtualized storage processors; and

FIG. 6 is a flowchart showing an example process for managing host datausing a VSP.

FIG. 7 is a block diagram of a non-disruptive upgrade (NDU) example at afirst time, T1.

FIG. 8 is a block diagram of the NDU example at a second time, T2, whichis after T1.

FIG. 9 is a block diagram of the NDU example at a third time, T3, whichis after T2.

FIG. 10 is a block diagram of the NDU example at a fourth time, T4,which is after T3.

FIGS. 11A and 11B provide a flowchart of an NDU procedure which isperformed on a data storage apparatus.

DETAILED DESCRIPTION Overview

Embodiments of the invention will now be described. It is understoodthat such embodiments are provided by way of example to illustratevarious features and principles of the invention, and that the inventionhereof is broader than the specific example embodiments disclosed.

An improved technique is directed to performing a non-disruptive upgrade(NDU) of software on a data storage apparatus having multiple physicalstorage processors (SPs) which access virtual storage processors (VSPs).The VSPs are capable of being moved from one physical SP to anotherduring NDU. Accordingly, a new version of the software can be installedon each physical SP while that physical SP is free of VSPs, i.e., withthe moved VSPs residing on one or more remaining physical SPs of thedata storage apparatus. Moreover, the new version of the software iscapable of being backwards compatible so that once all of the physicalSPs have the new version installed, a coordinated switchover can takeplace which commits the data storage apparatus to operating inaccordance with a new mode that is different from the backwardscompatible mode.

Data Storage Apparatus Details

An improved technique for managing host data in a data storage apparatusprovides virtualized storage processors (VSPs) as substantiallyself-describing and independent entities. Each VSP has its ownnamespace, which is independent of the namespace of any other VSP. EachVSP also has its own network address. Hosts may thus access VSPsdirectly, without having to include path information relative to the SPon which the VSPs are operated. VSPs can thus be moved from one physicalSP to another with little or no disruption to hosts, which may in manycases continue to access the VSPs on the new SPs using the same paths aswere used to access the VSPs on the original SPs.

In some examples, each VSP includes within its namespace a configurationfile system storing configuration settings for operating the VSP. Theseconfiguration settings include, for example, network interface settingsand internal settings that describe the VSPs “personality,” i.e., themanner in which the VSP interacts on the network. By providing thesesettings as part of the VSP itself (e.g., within the file systems of theVSP), the VSP can be moved from one physical SP to another substantiallyas a unit. The increased independence of the VSP from its hosting SPpromotes many aspects of VSP management, including, for example,migration, replication, failover, trespass, multi-tenancy, loadbalancing, and gateway support.

In some examples, the independence of VSPs is further promoted bystoring data objects of VSPs in the form of respective files. These dataobjects may include, for example, file systems, LUNs, virtual storagevolumes (vVols), and virtual machine disks (VMDKs). Each such file ispart of a set of internal file systems of the data storage apparatus.Providing data objects in the form of files of a set of internal filesystems promotes independence of VSPs and unifies management offile-based objects and block-based objects.

In accordance with improvements hereof, certain embodiments are directedto a method of managing host data on a data storage apparatus connectedto a network. The method includes storing a network address and a set ofhost data objects accessible within a namespace of a virtualized storageprocessor (VSP) operated by a physical storage processor of the datastorage apparatus. The namespace includes only names of objects that arespecific to the VSP. The method further includes receiving, by thephysical storage processor, a transmission over the network from a hostcomputing device. The transmission is directed to a network address andincludes an IO request designating a pathname to a host data object tobe written or read. The method still further includes identifying thehost data object designated by the IO request by (i) matching thenetwork address to which the transmission is directed with the networkaddress stored for the VSP, to identify the VSP as the recipient of theIO request, and (ii) locating the host data object within the namespaceof the VSP using the pathname. The IO request is then processed tocomplete the requested read or write operation on the identified hostdata object.

Other embodiments are directed to computerized apparatus and computerprogram products. Some embodiments involve activity that is performed ata single location, while other embodiments involve activity that isdistributed over a computerized environment (e.g., over a network).

An improved technique for managing host data in a data storage apparatusprovides virtualized storage processors (VSPs) as substantiallyself-describing and independent constructs.

FIG. 1 shows an example environment 100 in which embodiments of theimproved technique hereof can be practiced. Here, multiple hostcomputing devices (“hosts”) 110(1) through 110(N), access a data storageapparatus 116 over a network 114. The data storage apparatus 116includes a physical storage processor, or “SP,” 120 and storage 180. Thestorage 180 is provided, for example, in the form of hard disk drivesand/or electronic flash drives. Although not shown in FIG. 1, the datastorage apparatus 116 may include multiple SPs like the SP 120. Forinstance, multiple SPs may be provided as circuit board assemblies, or“blades,” which plug into a chassis that encloses and cools the SPs. Thechassis has a backplane for interconnecting the SPs, and additionalconnections may be made among SPs using cables. It is understood,however, that no particular hardware configuration is required, as anynumber of SPs (including a single one) can be provided and the SP 120can be any type of computing device capable of processing host IOs.

The network 114 can be any type of network, such as, for example, astorage area network (SAN), local area network (LAN), wide area network(WAN), the Internet, some other type of network, and/or any combinationthereof. In an example, the hosts 110(1-N) connect to the SP 120 usingvarious technologies, such as Fibre Channel, iSCSI, NFS, SMB 3.0, andCIFS, for example. Any number of hosts 110(1-N) may be provided, usingany of the above protocols, some subset thereof, or other protocolsbesides those shown. As is known, Fibre Channel and iSCSI areblock-based protocols, whereas NFS, SMB 3.0, and CIFS are file-basedprotocols. The SP 120 is configured to receive 10 requests 112(1-N) intransmissions from the hosts 110(1-N) according to both block-based andfile-based protocols and to respond to such IO requests 112(1-N) byreading or writing the storage 180.

The SP 120 is seen to include one or more communication interfaces 122,control circuitry (e.g., a set of processors 124), and memory 130. Thecommunication interfaces 122 include, for example, adapters, such asSCSI target adapters and network interface adapters, for convertingelectronic and/or optical signals received from the network 114 toelectronic form for use by the SP 120. The set of processors 124includes one or more processing chips and/or assemblies. In a particularexample, the set of processors 124 includes numerous multi-core CPUs.The memory 130 includes both volatile memory (e.g., RAM), andnon-volatile memory, such as one or more ROMs, disk drives, solid statedrives (SSDs), and the like. The set of processors 124 and the memory130 are constructed and arranged to carry out various methods andfunctions as described herein. Also, the memory 130 includes a varietyof software constructs realized in the form of executable instructions.When the executable instructions are run by the set of processors 124,the set of processors 124 are caused to carry out the operations of thesoftware constructs. Although certain software constructs arespecifically shown and described, it is understood that the memory 130typically includes many other software constructs, which are not shown,such as various applications, processes, and daemons.

As shown, the memory 130 includes an operating system 134, such as Unix,Linux, or Windows™, for example. The operating system 134 includes akernel 136. The memory 130 is further seen to include a container 132.In an example, the container 132 is a software process that provides anisolated userspace execution context within the operating system 134. Invarious examples, the memory 130 may include multiple containers likethe container 132, with each container providing its own isolateduserspace instance. Although containers provide isolated environmentsthat do not directly interact (and thus promote fault containment),different containers can be run on the same kernel 136 and cancommunicate with one another using inter-process communication (IPC)mediated by the kernel 136. Containers are well-known features of Unix,Linux, and other operating systems.

In the example of FIG. 1, only a single container 132 is shown. Runningwithin the container 132 is an IO stack 140 and multiple virtualizedstorage processors (VSPs) 150(1-3). The IO stack 140 provides anexecution path for host IOs (e.g., 112(1-N)) and includes a front end142 and a back end 144. The VSPs 150(1-3) each run within the container132 and provide a separate context for managing host data. In anexample, each VSP manages a respective set of host file systems and/orother data objects and uses servers and settings for communicating overthe network 114 with its own individual network identity. Although threeVSPs are shown, it is understood that the SP 120 may include as few asone VSP or as many VSPs as the computing resources of the SP 120 andstorage resources of the storage 180 allow.

Although the VSPs 150(1-3) each present an independent and distinctidentity, it is evident that the VSPs 150(1-3) are not, in this example,implemented as independent virtual machines. Rather, all VSPs 150(1-3)operate in userspace and employ the same kernel 136 of the SP 120.Although it is possible to implement the VSPs 150(1-3) as independentvirtual machines (each including a virtualized kernel), it has beenobserved that VSPs perform faster when the kernel 136 is notvirtualized.

Also, it is observed that the VSPs 150(1-3) all run within the container132, i.e., within a single userspace instance. Again, the arrangementshown reflects a deliberate design choice aimed at optimizing VSPperformance. It is understood, though, that alternative implementationscould provide different VSPs in different containers, or could beprovided without containers at all.

The memory 130 is further seen to store a configuration database 170.The configuration database 170 stores system configuration information,including settings related to the VSPs 150(1-3) and their data objects.In other implementations, the configuration database 170 is storedelsewhere in the data storage apparatus 116, such as on a disk driveseparate from the SP 120 but accessible to the SP 120, e.g., over abackplane or network.

In operation, the hosts 110(1-N) issue IO requests 112(1-N) to the datastorage apparatus 116. The IO requests 112(1-N) may include bothblock-based requests and file-based requests. The SP 120 receives the IOrequests 112(1-N) at the communication interfaces 122 and passes the IOrequests to the IO stack 140 for further processing.

At the front end 142 of the IO stack 140, processing includesassociating each of the IO requests 112(1-N) with a particular one ofthe VSPs 150(1-3). In an example, each VSP stores a network address(e.g., an IP address) in a designated location within its file systems.The front end 142 identifies the network address to which each IOrequest is directed and matches that address with one of the networkaddresses stored with the VSPs 150(1-3). The front end 142 thus uses thenetwork address to which each IO request is sent to identify the VSP towhich the IO request is directed. Further processing of the IO requestis then associated (e.g., tagged) with an identifier of the matchingVSP, such that the IO request is processed within a particular VSPcontext. Any data logging, metrics collection, fault reporting, ormessages generated while the IO request is being processed are storedwith the associated VSP (e.g., in a file system dedicated to the VSP).Also, any path information provided with the IO request (e.g., to aparticular directory and file name) is interpreted within the namespaceof the identified VSP.

Processing within the front end 142 may further include caching dataprovided with any write IOs and mapping host data objects (e.g., hostfile systems, LUNs, vVols, VMDKs, etc.) to underlying files stored in aset of internal file systems. Host IO requests received for reading andwriting both file systems and LUNs are thus converted to reads andwrites of respective files. The IO requests then propagate to the backend 144, where commands are executed for reading and/or writing thephysical storage 180.

In an example, processing through the IO stack 140 is performed by a setof threads maintained by the SP 120 in a set of thread pools. When an IOrequest is received, a thread is selected from the set of thread pools.The IO request is tagged with a VSP identifier, and the selected threadruns with the context of the identified VSP. Typically, multiple threadsfrom different thread pools contribute to the processing of each IOrequest (there are many processing layers). Multiple threads from thethread pools can process multiple IO requests simultaneously, i.e., inparallel, on the data objects of any one VSP or multiple VSPs.

Although FIG. 1 shows the front end 142 and the back end 144 together inan “integrated” form, the front end 142 and back end 144 mayalternatively be provided on separate SPs. For example, the IO stack 140may be implemented in a “modular” arrangement, with the front end 142 onone SP and the back end 144 on another SP. The IO stack 140 may furtherbe implemented in a “gateway” arrangement, with multiple SPs runningrespective front ends 142 and with a back end provided within a separatestorage array. The back end 144 performs processing that is similar toprocessing natively included in many block-based storage arrays.Multiple front ends 142 can thus connect to such arrays without the needfor providing separate back ends. In all arrangements, processingthrough both the front end 142 and back end 144 is preferably taggedwith the particular VSP context such that the processing remainsVSP-aware.

FIG. 2 shows portions of the front end 142 in additional detail. Here,and describing the architecture generally without regard to anyparticular VSP, it is seen that a set of lower-deck file systems 202represents LUNs and host file systems in the form of files. Any numberof lower-deck file systems 202 may be provided. In one arrangement, asingle lower-deck file system may include, as files, any number of LUNsand/or host file systems, as well as their snaps (i.e., point-in-timecopies). In another arrangement, a different lower-deck file system isprovided for each primary object to be stored, e.g., for each LUN andfor each host file system. Additional arrangements provide groups ofhost file systems and/or groups of LUNs together in a single lower deckfile system. The lower-deck file system for any object may include afile storing the object itself, as well as files storing any snaps ofthe object. Each lower-deck file system 202 has an inode table (e.g.,232, 242), which provides a unique inode for each file stored in thelower-deck file system. The inode table of each lower-deck file systemstores properties of each file in the respective lower-deck file system,such as ownership and block locations at which the file's data arestored. Lower-deck file systems are built upon storage elements managedby a storage pool 204.

The storage pool 204 organizes elements 250 of the storage 180 in theform of slices. A “slice” is an increment of storage space, such as 256MB in size, which is obtained from the storage 180. The pool 204 mayallocate slices to lower-deck file systems 202 for use in storing theirfiles. The pool 204 may also deallocate slices from lower-deck filesystems 202 if the storage provided by the slices is no longer required.In an example, the storage pool 204 creates slices by accessing RAIDgroups formed from the storage 180, dividing the RAID groups into FLUs(Flare LUNs), and further dividing the FLU's into slices.

Continuing with reference to the example shown in FIG. 2, a user objectlayer 206 includes a representation of a LUN 210 and of an HFS (hostfile system) 212, and a mapping layer 208 includes a LUN-to-file mapping220 and an HFS-to-file mapping 222. The LUN-to-file mapping 220 maps theLUN 210 to a first file F1 (236), and the HFS-to-file mapping 222 mapsthe HFS 212 to a second file F2 (246). Through the LUN-to-file mapping220, any set of blocks identified in the LUN 210 by a host IO request ismapped to a corresponding set of blocks within the first file 236.Similarly, through the HFS-to-file mapping 222, any file or directory ofthe HFS 212 is mapped to a corresponding set of blocks within the secondfile 246. The HFS 212 is also referred to herein as an “upper-deck filesystem,” which is distinguished from the lower-deck file systems 202,which are for internal use.

In this example, a first lower-deck file system 230 includes the firstfile 236 and a second lower-deck file system 240 includes the secondfile 246. Each of the lower-deck file systems 230 and 240 includes aninode table (232 and 242, respectively). The inode tables 232 and 242provide information about files in respective lower-deck file systems inthe form of inodes. For example, the inode table 232 of the firstlower-deck file system 230 includes an inode 234, which providesfile-specific information about the first file 236. Similarly, the inodetable 242 of the second lower-deck file system 240 includes an inode244, which provides file-specific information about the second file 246.The information stored in each inode includes location information(e.g., block locations) where the respective file is stored, and maythus be accessed as metadata to identify the locations of the files 236and 246 in the storage 180.

Although a single file is shown for each of the lower-deck file systems230 and 240, it is understood that each of the lower-deck file systems230 and 240 may include any number of files, each with its own entry inthe respective inode table. In one example, each lower-deck file systemstores not only the file F1 or F2 for the LUN 210 or HFS 212, but alsosnaps of those objects. For instance, the first lower-deck file system230 stores the first file 236 along with a different file for every snapof the LUN 210. Similarly, the second lower-deck file system 240 storesthe second file 246 along with a different file for every snap of theHFS 212.

As shown, a set of slices 260 is allocated by the storage pool 204 forstoring the first file 236 and the second file 246. In the exampleshown, slices S1 through S4 are used for storing the first file 236, andslices S5 through S7 are used for storing the second file 246. The datathat make up the LUN 210 are thus stored in the slices S1 through S4,whereas the data that make up the HFS 212 are stored in the slices S5through S7.

In some examples, each of the lower-deck file systems 230 and 240 isassociated with a respective volume, such as a sparse LUN. Sparse LUNsprovide an additional layer of mapping between the lower-deck filesystems 202 and the pool 204 and allow the lower-deck file systems tooperate as file systems normally do, by accessing underlying volumes.Additional details about sparse LUNs and their relation to lower-deckfile systems may be found in U.S. Pat. No. 7,631,155, which is herebyincorporated by reference in its entirety. The incorporated patent usesthe term “container file system” to refer to a construct similar to thelower-deck file system disclosed herein.

Although the example of FIG. 2 shows storage of a LUN 210 and a hostfile system 212 in respective lower-deck file systems 230 and 240, it isunderstood that other data objects may be stored in one or morelower-deck file systems in a similar manner. These may include, forexample, file-based vVols, block-based vVols, and VMDKs.

FIG. 3 shows an example set of components of the data storage apparatus116 that are associated with a particular VSP 300 (i.e., any of the VSPs150(1-3)). The components shown in FIG. 3 include components that aremanaged in the context of the VSP 300 and components that form the“personality” of the VSP 300. These components may be referred to hereinas “included” within the VSP 300, by which it is meant that thecomponents are associated with the VSP 300 within the data storageapparatus 116 and are not associated with any other VSP. It is thus seenthat the VSP 300 “includes” a number of lower-deck file systems hostingvarious host data objects, as well as internal data objects.

For example, the VSP 300 includes a first lower-deck file system 310 anda second lower-deck file system 320. The first lower-deck file system310 includes a file FA, which provides a file representation of a firsthost file system 312. Similarly, the second lower-deck file system 320includes a file FB, which provides a file representation of a secondhost file system 322. The host file systems 312 and 322 are upper-deckfile systems, which may be made available to hosts 110(1-N) for storingfile-based host data. HFS-to-file mappings, like the HFS-to-file mapping222, are understood to be present (although not shown in FIG. 3) forexpressing the files FA and FB in the form of upper-deck file systems.Although only two host file systems 312 and 322 are shown, it isunderstood that the VSP 300 may include any number of host file systems.In an example, a different lower-deck file system is provided for eachhost file system. The lower-deck file system stores the filerepresentation of the host file system, and, if snaps are turned on, anysnaps of the host file system. In a similar manner to that described inconnection with FIG. 2, each of the lower-deck file systems 310 and 320includes a respective inode table, allowing the files FA and FB andtheir snaps to be indexed within the respective lower-deck file systemsand accessed within the storage 180.

In some examples, the VSP 300 also includes one or more lower-deck filesystems for storing file representations of LUNs. For example, alower-deck file system 330 stores a file FC, which provides a filerepresentation of a LUN 332. A LUN-to-file mapping (not shown butsimilar to the mapping 320) expresses the file FC in the form of a LUN,which may be made available to hosts 110(1-N) for storing block-basedhost data. In an example, the lower-deck file system 330 stores not onlythe file FC, but also snaps thereof, and includes an inode table inessentially the manner described above.

The VSP 300 further also includes a lower-deck file system 340. In anexample, the lower-deck file system 340 stores file representations FDand FE of two internal file systems of the VSP 300—a root file system342 and a configuration file system 344. In an alternative arrangement,the files FD and FE are provided in different lower-deck file systems.In an example, the lower-deck file system 340 also stores snaps of thefiles FD and FE, and files are accessed within the lower-deck filesystem 340 via file system-to-file mappings and using an inode table,substantially as described above.

In an example, the root file system 342 has a root directory, designatedwith the slash (“\”), and sub-directories as indicated. Any number ofsub-directories may be provided within the root file system in anysuitable arrangement with any suitable file structure; the example shownis merely illustrative. As indicated, one sub-directory (“Local”)stores, for example, within constituent files, information about thelocal environment of the SP, such as local IP sub-net information,geographical location, and so forth. Another sub-directory (“Rep”)stores replication information, such as information related to anyongoing replication sessions. Another sub-directory (“Cmd Svc”) storescommand service information, and yet another sub-directory (“MPs”)stores mount points.

In the example shown, the directory “MPs” of the root file system 342provides mount points (e.g., directories) on which file systems aremounted. For example, the host file systems 312 and 322 are respectivelymounted on mount points MP1 and MP2, and the configuration file system344 is mounted on the mount point MP3. In an example, establishment ofthe mount points MP1-MP3 and execution of the mounting operations formounting the file systems 312, 322, 344 onto the mount points MP1-MP4are provided in a batch file stored in the configuration file system 344(e.g., in Host Objects). It is understood that additional mount pointsmay be provided for accommodating additional file systems.

The root file system 342 has a namespace, which includes the names ofthe root directory, sub-directories, and files that belong to the rootfile system 342. The file systems 312, 322, and 344 also each haverespective namespaces. The act of mounting the file systems 312, 322,and 344 onto the mount points MP1, MP2, and MP3 of the root file system342 serves to join the namespace of each of the file systems 312, 322,and 344 with the namespace of the root file system 342, to form a singlenamespace that encompasses all the file systems 312, 322, 342, and 344.This namespace is specific to the VSP 300 and is independent ofnamespaces of any other VSPs.

Also, it is understood that the LUN 332 is also made available to hosts110(1-N) through the VSP 300. For example, hosts 110(1-N) can send readand write IO requests to the LUN 332 (e.g., via Fibre Channel and/oriSCSI commands) and the SP 120 services the requests for the VSP 300,e.g., by operating threads tagged with the context of the VSP 300.Although FIG. 3 shows both the LUN 322 and the host file systems 312 and322 together in a single VSP 300, other examples may provide separateVSPs for LUNs and for file systems.

Although the VSP 300 is seen to include file systems and LUNs, otherhost objects may be included, as well. These include, for example,file-based vVols, block-based vVols, and VMDKs. Such host objects may beprovided as file representations in lower-deck file systems and madeavailable to hosts 110(1-N).

As its name suggests, the configuration file system 344 storesconfiguration settings for the VSP 300. These settings include settingsfor establishing the “personality” of the VSP 300, i.e., the manner inwhich the VSP 300 interacts over the network 114. Although theconfiguration file system 344 is shown with a particular directorystructure, it is understood that any suitable directory structure can beused. In an example, the configuration file system 344 stores thefollowing elements:

IF Config.

-   -   Interface configuration settings of any network interface used        for processing IO requests and tagged with a context of the VSP        300. IF Config includes the IP address of the VSP, as well as        related network information, such as sub-masks and related IP        information.

CIFS.

Configuration settings and names of one or more CIFS servers used in thecontext of the VSP 300. The CIFS servers manage IO requests provided inthe CIFS protocol. By including the CIFS configuration within theconfiguration file system 344, the CIFS configuration becomes part ofthe VSP 300 itself and remains with the VSP 300 even as the VSP 300 ismoved from one SP to another SP. This per-VSP configuration of CIFS alsopermits each VSP to have its own customized CIFS settings, which may bedifferent from the settings of CIFS servers used by other VSPs.

NFS.

Configuration settings and names of one or more NFS servers used in thecontext of the VSP 300. The NFS servers manage IO requests provided inthe NFS protocol. By including the NFS configuration within theconfiguration file system 344, the NFS configuration becomes part of theVSP 300 itself and remains with the VSP 300 even as the VSP 300 is movedfrom one SP to another SP. This per-VSP configuration of NFS alsopermits each VSP to have its own customized NFS settings, which may bedifferent from the settings of NFS servers used by other VSPs.

Exports.

NFS exports, CIFS shares, and the like for all supported protocols. Forsecurity and management of host access, users are typically given accessonly to specified resources mounted to the root file system 342, e.g.,host file systems, sub-directories of those file systems, and/orparticular LUNs. Access to these resources is provided by performingexplicit export/share operations, which expose entry points to theresources for host access. In an example, these export/share operationsare included within one or more batch files, which may be executed whenthe VSP 300 is started. Exports are typically VSP-specific, and dependupon the particular data being hosted and the access required.

CAVA/NDMP:

CAVA (Celerra Anti-Virus Agent) configuration file, including locationof external server for performing virus checking operations. NDMP(Network Data Management Protocol) provides backup configurationinformation. CAVA and NDMP settings are configurable on a per-VSP basis.

NIS/DNS/LDAP:

Local configurations and locations of external servers for providingresolution of IP addresses. NIS (Network Information Service), DNS(Directory Name System), and LDAP (Lightweight Directory AccessProtocol) settings are configurable on a per-VSP basis. The DNSconfiguration stores local host name and domain name of the VSP 300, aswell as the location of a DNS server for resolving host names.

Host Objects:

Identifiers for all host file systems (e.g., 312 and 322), LUNs (e.g.,LUN 332), and other host objects included within the VSP 300. Hostobjects may also include batch files and/or lists of instructions forestablishing mount points in the root file system 342 and for mountingthe host file system(s) and LUN(s) to the mount points.

Parameters:

Low-level settings (e.g., registry settings) for configuring VSP 300.These include cache settings and settings for specifying a maximumnumber of threads running on the SP 120 that may be used to service IOrequests within the context of the VSP 300. Parameters are configurableon a per-VSP basis.

Statistics:

Metrics, log files, and other information pertaining to activitieswithin the context of the VSP 300. Statistics are updated as theyaccumulate.

Many configuration settings are established at startup of the VSP 300.Some configuration settings are updated as the VSP 300 is operated. Theconfiguration file system 344 preferably does not store host data.

Although FIG. 3 has been shown and described with reference to aparticular VSP 300, it is understood that all of the VSPs 150(1-3) mayinclude a root file system, a configuration file system, and at leastone host file system or LUN, substantially as shown. Particular hostobjects and configuration settings differ, however, from one VSP toanother.

By storing the configuration settings of VSPs within the file systems ofthe VSPs themselves and providing a unique namespace for each VSP, VSPsare made to be highly independent, both of other VSPs and of theparticular SPs on which they are provided. For example, migrating a VSPfrom a first data storage system to a second data storage systeminvolves copying its lower-deck file systems (or some subset thereof)from a source SP on the first data storage system to a target SP on thesecond, starting the VSP's servers on the target SP in accordance withthe configuration settings, and resuming operation on the target SP. Asthe paths for accessing data objects on VSPs are not rooted to the SPson which they are run, hosts may often continue to access migrated VSPsusing the same instructions as were used prior to moving the VSPs.Similar benefits can be enjoyed when moving a VSP from one SP to anotherSP in the same data storage system. storage system. To move a VSP from afirst SP to a second SP, The VSP need merely be shut down (i.e., haveits servers stopped) on the first SP and resumed (i.e., have its serversstarted up again) on the second SP.

FIG. 4 shows an example record 400 of the configuration database 170,which are used to define a particular VSP having a VSP identifier (ID)410. The VSP ID 410 may identify one of the VSPs 150(1-3) or some otherVSP of the data storage apparatus 116. The record 400 specifies, forexample, an owning SP (physical storage processor), authentication, andidentifiers of the data objects associated with the listed VSP. The dataobject identifiers include identifiers of the root file system,configuration file system, and various host file systems (or other hostobjects) that may be accessed in the context of the listed VSP. Therecord 400 may also identify the lower-deck file system used to storeeach data object. The record 400 may further specify host interfacesthat specify IO protocols that the listed VSP is equipped to handle.

Although FIG. 4 shows only a single record 400 for a single VSP, it isunderstood that the configuration database 170 may store records, likethe record 400, for any number of VSPs, including all VSPs of the datastorage apparatus 116. During start-up of the data storage apparatus116, or at some other time, a computing device of the data storageapparatus 116 reads the configuration database 170 and launches aparticular VSP or a group of VSPs on the identified SPs. As a VSP isstarting, the SP that owns the VSP reads the configuration settings ofthe configuration file system 344 to configure the various servers ofthe VSP and to initialize its communication protocols. The VSP may thenbe operated on the identified SP, i.e., the SP may then be operated withthe particular VSP's context.

It is understood that VSPs 150(1-3) operate in connection with the frontend 142 of the IO stack 140. The VSPs 150(1-3) thus remain co-locatedwith their respective front ends 142 in modular and gatewayarrangements.

FIGS. 5A and 5B show two different example arrangements of VSPs. In FIG.5A, the VSPs 150(1-3) access the storage pool 204. Thus, the lower-deckfile systems of the VSPs 150(1-3) all derive the slices needed to storetheir underlying file systems and other data objects from the pool 204.In FIG. 5B, multiple storage pools 550(1-3) are provided, one for eachof the VSPs 150(1-3), respectively. Providing different pools forrespective VSPs promotes data isolation among the VSPs, and may bebetter suited for applications involving multiple tenants in which eachtenant's data must be kept separate from the data of other tenants.

FIG. 6 shows an example method 600 for managing host data on a datastorage apparatus connected to a network. The method 600 that may becarried out in connection with the data storage apparatus 116. Themethod 600 is typically performed by the software constructs, describedin connection with FIGS. 1-3, which reside in the memory 130 of thestorage processor 120 and are run by the set of processors 124. Thevarious acts of the method 600 may be ordered in any suitable way.Accordingly, embodiments may be constructed in which acts are performedin orders different from those illustrated, which may include performingsome acts simultaneously, even though the acts are shown as sequentialin the illustrated embodiments.

At step 610, a network address and a set of host data objects are storedin a data storage apparatus. The set of host data objects are accessiblewithin a namespace of a virtualized storage processor (VSP) operated bya physical storage processor of the data storage apparatus. Thenamespace includes only names of objects that are specific to the VSP.For example, an IP address of the VSP 300 is stored in a file of adirectory of the configuration file system 344. The VSP 300 runs on theSP 120 of the data storage apparatus 116. A set of host objects,including host file systems 312 and 322, and LUN 332, are also stored inthe data storage apparatus 116. These host objects are made accessiblewithin the namespace of the VSP 300 by mounting these data objects tomount points MP1-MP4 within the root file system 342 and thus mergingtheir namespaces with that of the root file system 342. The resultingmerged namespace includes only names of objects that are specific to theVSP 300.

At step 612, a transmission is received by the physical storageprocessor over the network from a host computing device. Thetransmission is directed to a network address and includes an IO requestdesignating a pathname to a host data object to be written or read. Forexample, the SP 120 receives a transmission over the network 114 fromone of the hosts 110(1-N). The transmission is directed to a particularIP address and includes an IO request (e.g., one of 112(1-N)). The IOrequest designates a location of a host data object to be written orread (e.g., a pathname for a file-based object or a block designationfor a block-based object). The location may point to any of the hostfile systems 312 or 322, to the LUN 332, or to any file or offset rangeaccessible through the host file systems 312 or 322 or the LUN 332,respectively. The location may also point to a vVol or VMDK, forexample, or to any other object which is part of the namespace of theVSP 300.

At step 614, the host data object designated by the IO request isidentified by (i) matching the network address to which the transmissionis directed with the network address stored for the VSP, to identify theVSP as the recipient of the IO request, and (ii) locating the host dataobject within the namespace of the VSP using the pathname. For example,each of the VSPs 150(1-3) stores an IP address in its configuration filesystem 344. When an IO request is received, an interface running withinthe front end 142 of the IO stack 140 checks the IP address to which theIO request is directed and matches that IP address with one of the IPaddresses stored for the VSPs 150(1-3). The VSP whose IP address matchesthe IP address to which the IO request is directed is identified as therecipient of the IO request. The IO request arrives to the SP 120 with apathname to the host data object to be accessed. The front end 142 looksup the designated pathname within the identified VSP to identify theparticular data object to which the IO request is directed.

At step 616, the IO request is processed to complete the requested reador write operation on the identified host data object. For example, thefront end 142 and the back end 144 process the IO request to perform anactual read or write to the designated host data object on the storage180.

An improved technique has been described for managing host data in adata storage apparatus. The technique provides virtualized storageprocessors (VSPs) as substantially self-describing and independententities. Each VSP has its own namespace, which is independent of thenamespace of any other VSP. Each VSP also has its own network address.Hosts may thus access VSPs directly, without having to include pathinformation relative to the SP on which the VSP is operated. VSPs canthus be moved from one physical SP to another with little or nodisruption to hosts, which may continue to access the VSPs on the newSPs using the same paths as were used when the VSPs were running on theoriginal SPs.

As used throughout this document, the words “comprising,” “including,”and “having” are intended to set forth certain items, steps, elements,or aspects in an open-ended fashion. Also, and unless explicitlyindicated to the contrary, the word “set” as used herein indicates oneor more of something. Although certain embodiments are disclosed herein,it is understood that these are provided by way of example only and theinvention is not limited to these particular embodiments.

Having described certain embodiments, numerous alternative embodimentsor variations can be made. For example, embodiments have been shown anddescribed in which host file systems, LUNs, vVols, VMDKs, and the likeare provided in the form of files of underlying lower-deck file systems.Although this arrangement provides advantages for simplifying managementof VSPs and for unifying block-based and file-based operations, the useof lower-deck file systems is merely an example. Indeed, host filesystems, LUNs, vVols, VMDKs, and the like may be provided for VSPs inany suitable way.

Also, although the VSPs 150(1-3) are shown and described as userspaceconstructs that run within the container 132, this is also merely anexample. Alternatively, different VSPs may be provided in separatevirtual machines running on the SP 120. For example, the SP 120 isequipped with a hypervisor and a virtual memory manager, and each VSPruns in a virtual machine having a virtualized operating system.

Also, the improvements or portions thereof may be embodied as anon-transient computer-readable storage medium, such as a magnetic disk,magnetic tape, compact disk, DVD, optical disk, flash memory,Application Specific Integrated Circuit (ASIC), Field Programmable GateArray (FPGA), and the like (shown by way of example as medium 650 inFIG. 6). Multiple computer-readable media may be used. The medium (ormedia) may be encoded with instructions which, when executed on one ormore computers or other processors, implement the various methodsdescribed herein. Such medium (or media) may be considered an article ofmanufacture or a machine, and may be transportable from one machine toanother.

Non-Disruptive Upgrade Details

FIGS. 7-10 illustrate non-disruptive upgrade of a data storage apparatus116. FIG. 7 shows two physical SPs 120(A), 120(B) (collectively,physical SPs 120) at a first operating time, T1, at the beginning ofNDU. FIG. 8 shows the physical SPs 120 at a second operating time, T2,after T1. FIG. 9 shows the physical SPs 120 at a third operating time,T3, after T2. FIG. 10 shows the physical SPs 120 at a fourth operatingtime, T4, after T3.

By way of example only, there is a storage pool 204, a user interface800, and a configuration database 170. The storage pool 204 is formedfrom a set of storage units and, as mentioned earlier, contains a set oflower deck file systems 202 (also see FIG. 2). The user interface 800takes input from and provides output to a user (e.g., an administrator)and may take the form of a user workstation or terminal in communicationwith the processing circuitry (i.e., the physical SPs 120) of the datastorage apparatus 116 to provide the user with a command line interfaceor GUI.

As shown in FIG. 7, the storage pool 204 provides storage for VSPs150(A)(1), 150(A)(2) which are owned by the physical SP 120(A). Inparticular, a lower-deck file 802(A)(1) contains a VSP configurationfile system 344(A)(1) which defines a personality for the VSP 150(A)(1)(also see FIG. 3). Similarly, another lower-deck file 802(A)(2) containsanother VSP configuration file system 344(A)(2) which defines apersonality for the VSP 150(A)(2).

Additionally and as shown in FIG. 7, a lower-deck file 804(A)(1)contains a host file system 806(A)(1) for use by a host. Similarly,another lower-deck file 804(A)(2) contains another host file system806(A)(2) for use by a host. The personalities, or operatingenvironments in which the host file systems 806(A)(1), 806(A)(2) reside,are defined by the VSP configuration file systems 344(A)(1), 344(A)(2),respectively. Recall that the VSP configuration file systems 344 andhost file systems 806 are mounted to the respective root file systems(or root structures) of the VSPs 150 (see dashed lines in FIGS. 7 and 8,and also see FIG. 3).

Furthermore and as shown in FIG. 7, the storage pool 204 furtherprovides storage for a VSP 150(B)(1) which is owned by the physical SP120(B). In particular, a lower-deck file 802(B)(1) contains a VSPconfiguration file system 344(B)(1) which defines a personality for theVSP 150(B)(1), and a lower-deck file 804(B)(1) contains a host filesystem 806(B)(1) for use by a host. Again, the VSP configuration filesystem 344(B)(1) and the host file system 806(B)(1) are mounted to theroot file system of the VSP 150(B)(1).

It should be understood that the configuration database 170 includes aset of records 400 (also see FIG. 4) which is used to manage and trackownership of various constructs/objects of the data storage apparatus116. Along these lines, the configuration database 170 indicates, foreach VSP 150, a particular physical SP 120 that owns that VSP 150.Likewise, the configuration database 170 indicates, for each lower-deckfile 802, 804, a particular VSP 150 that owns that that lower-deck file802, 804 (i.e., the particular VSP to which that lower-deck file 802,804 is mounted), and so on.

In this example, the physical SP 120(A) owns VSPs 150(A)(1), 150(A)(2).Similarly, the physical SP 120(B) owns VSP 150(B)(1). It should beunderstood that, in some situations, other storage pools 204 may storageother VSPs 150 and that the physical SPs 120 may own those other VSPs150 in addition to the VSPs 150 shown in the figures.

During operating time T1 which is at the beginning of NDU, it should beunderstood that the physical SP 120(A) processes host input/output (I/O)requests directed to the host file systems 806(A)(1), 806(A)(2) whichare mounted to the VSPs 150(A)(1), 150(A)(2), respectively. Similarly,the physical SP 120(B) processes host I/O requests directed to the hostfile system 806(B)(1) which is mounted to the VSP 150(B)(1). 150(B)(1).

Now, suppose that a user wishes to begin the NDU process. In somearrangements, the user enters a single upgrade command 810 via the userinterface 800. In other arrangements, the user enters a series ofupgrade-related commands 810 via the user interface 800 for more precisecontrol and monitoring during the NDU process (i.e., to carry out NDU ina step by step manner). Accordingly, it should be understood that eachstep of the process may be performed sequentially in an automated manner(e.g., in response to a single user command 810) or in response tomanually entered incremental user commands 810.

Initially and with reference to FIG. 7, an initial version of softwareis installed on each physical SP 120. In accordance with that initialversion, each physical SP 120 may process host I/O requests in aparticular manner or according to a particular protocol, e.g., using aparticular order of operations, in a particular format, using aparticular semantic, updating and/or relying on particular metadata, andso on.

However, the goal of the NDU process is to finish with a new version 812of the software is installed on each physical SP 120, and with theplacement of the VSPs 150 as originally shown in FIG. 7. Along theselines, the new version 812 is backwards compatible and, after NDU, eachphysical SP 120 may process host I/O requests in the same particularmanner as with the initial version. Alternatively, each physical SP 120may process host I/O requests in a different manner than that of theinitial version if the data storage apparatus 116 is directed to committo the new manner or new protocol of the new software version (i.e., totake advantage of the new features).

As shown by the arrows in FIG. 7, the VSPs 150(A)(1), 150(A)(2) on thephysical SP 120(A) are moved from the physical SP 120(A) to the physicalSP 120(B) (see the arrows 820(1), 820(2) in FIG. 7). As the VSPs 150 aremoved from one physical SP 120 to another, the configuration database170 is updated so that the current location of each VSP 150 is trackedby the data storage apparatus 116. It should be understood that “a VSPon a particular physical SP” is a general description meaning that theparticular physical SP controls and has access to that VSP.

It should be further understood that transfer of the VSPs 150 betweenphysical SPs 120 may occur incrementally. Such operation enables aparticular VSP 150 to move from one physical SP 120 to another quicklywithout significant contention for resources thus providing the userwith a high quality of service, e.g., high/continuous availability, fastresponse time, etc. Additionally, it should be understood that moving aVSP 150 may involve draining queues/caches/etc. and completing partiallystarted operations prior to transferring the VSP 150 to another physicalSP 120 in order to prevent data loss. Also, it should be understood thatthis transfer operation of a VSP 150 from one physical SP 120 to anotherphysical SP 120 may be suitable for other activities such as loadbalancing VSPs 150 among physical SPs 120.

At time T2 and as shown in FIG. 8, there are no VSPs 150 currently on(i.e., accessed by) the physical SP 120(A). Rather, all of the VSPs 150now reside on the physical SP 120(B). Accordingly, the physical SP120(B) now processes all of the host I/O requests for the data storageapparatus 116. Along these lines, the physical SP 120(B) processes hostI/O requests directed to the host file systems 806(A)(1), 806(A)(2),806(B)(1) which are mounted to the VSPs 150(A)(1), 150(A)(2), 150(B)(1),respectively.

At this point, the physical SP 120(A) is ready for installation of thenew version 812 of the software. Accordingly, the new version 812 of thesoftware is installed on the physical SP120(A) while the physical SP120(B) continues to process all of the host I/O requests for the datastorage apparatus 116.

Once the new version 812 of the software has been installed on thephysical SP 120(A), the physical SP 120(A) is configured to operate in abackwards compatible mode. That is, even though the new software version812 is running on the physical SP 120(A), the physical SP 120(A) isconfigured to process host I/O requests in the same manner as that forthe initial software version. At this point, all of the VSPs 150 on thephysical SP 120(B) are moved to the physical SP 120(A) (see the arrows830(1), 830(2), 830(3) in FIG. 8), and the configuration database 170 isagain updated.

At time T3 and as shown in FIG. 9, there are no VSPs 150 currently onthe physical SP 120(B). Rather, all of the VSPs 150 now reside on thephysical SP 120(A). In particular, the VSPs 150(A)(1), 150(A)(2) whichstarted on the physical SP 120(A) as well as the VSP 150(B)(1) whichstarted on the physical SP 120(B) have moved from the physical SP 120(B)to the physical SP 120(A). Accordingly, the physical SP 120(A) nowprocesses all of the host I/O requests for the data storage apparatus116. That is, the physical SP 120(A) processes host I/O requestsdirected to the host file systems 806(A)(1), 806(A)(2), 806(B)(1) whichare mounted to the VSPs 150(A)(1), 150(A)(2), 150(B)(1), respectively.

At this point, the physical SP 120(B) is now ready for installation ofthe new version 812 of the software. Accordingly, the new version 812 ofthe software is installed on the physical SP120(B) while the physical SP120(A) continues to process all of the host I/O requests for the datastorage apparatus 116.

Once the new version of the software has been installed on the physicalSP 120(B), the physical SP 120(B) is configured to operate in abackwards compatible mode. That is, even though the new software version812 is running on the physical SP 120(B), the physical SP 120(B) isconfigured to process host I/O requests in the same manner as that forthe initial software version. At this point, all of the VSPs 150 thatare owned by the physical SP 120(B) (namely, the VSP 150(B)(1)) aremoved back to the physical SP 120(B) (see arrow 840 in FIG. 9), andagain the configuration database 170 is updated. The VSPs that are ownedby the physical SP 120(A) (namely, the VSPs 150(A)(1), 150(A)(2)) remainon the physical SP 120(A).

At time T4 and as shown in FIG. 10, each VSP 150 resides on its primaryowner and the NDU process is essential finished. In particular, thephysical SP 120(A) processes host input/output (I/O) requests directedto the host file systems 806(A)(1), 806(A)(2) which are mounted to theVSPs 150(A)(1), 150(A)(2), respectively. Similarly, the physical SP120(B) processes host I/O requests directed to the host file system806(B)(1) which is mounted to the VSP 150(B)(1). Additionally, the newversion 812 of the software is now installed on all of the physical SPs120 which are currently running in backwards compatible mode to processhost I/O requests in the same manner as that of the initial version ofthe software.

At this point, the user may commit the data storage apparatus 116 toprocessing host I/O requests in the manner of the new version 812 oraccording to the new protocol. Any new processing features or functionsbecome available once the user commits to the new version 812 of thesoftware. However, the user may decide not to commit the data storageapparatus 116 to processing host I/O requests in accordance with the newmode. Rather, the user may wish to continue operating the data storageapparatus 116 in backwards compatible mode to process I/O requests inthe same manner as that of the initial version indefinitely, or until amore convenient switchover time.

If the user wishes to defer switchover indefinitely, the user enters acompletion command 810. In response, the data storage apparatus 116deems the NDU process to be complete and continues to operate with eachphysical SP 120 using the new version 812 of the software in thebackward compatible mode.

Eventually, if the user is ready to process host I/O requests in the newmanner, the user enters a switchover command 810 into the user interface800. The physical SPs 120 respond to the switchover command 810 byprocessing newly received I/O requests in the new manner. It should beunderstood that the switchover process may involve drainingqueues/caches/etc. and completing partially started operations prior toswitchover in order to prevent data loss.

It should be understood that the physical SPs 120 may be configured toconcurrently handle file-based and block-based I/O requests from hosts.In these arrangements, the data storage apparatus 116 trespassesblock-based processing among the physical SPs 120 in tandem with movingVSPs 150 among the physical SPs 120 to remove processing of all host I/Orequests from each physical SP 120 when the new version 812 of thesoftware is installed on that physical SP 120.

FIGS. 11A and 11B provide a flowchart of a procedure 900 which isperformed by the data storage apparatus 116 for NDU. With reference toFIG. 11A, at 902, with (i) a first physical SP 120 initially using afirst set of VSPs 150 to define a first set of operating environmentsfor a first set of host file systems, (ii) a second physical SP 120initially using a second set of VSPs 150 to define a second set ofoperating environments for a for a second set of host file systems, and(iii) an initial version of the software being installed on each of thefirst and second physical SPs 120, the physical SPs 120 process hostinput/output (I/O) requests on the host file systems (also see FIG. 7).

At 904, the first set of VSPs 150 is moved from the first physical SP120 to the second physical SP 120 to provision the second physical SP120 to process host I/O requests concurrently on the first and secondsets of host file systems using the first and second sets of VSPs 150(also see FIG. 8). It should be understood that the configurationdatabase 170 is updated to reflect the current locations of the VSPs 150during NDU. It should be further understood that, if the data storageapparatus 116 concurrently performs block-based processing of host I/Orequests, any block-based processing performed by the first physical SP120 is trespassed over to the second physical SP 120 at this time aswell. Accordingly, the first physical SP 120 is now free to receive asoftware upgrade.

At 906, after the first set of VSPs 150 is moved from the first physicalSP 120 to the second physical SP 120 and while the second physical SP120 processes host I/O requests concurrently on the first and secondsets of host file systems using the first and second sets of VSPs 150, anew version 812 of the software is installed on the first physical SP120 (FIG. 8). As mentioned earlier, the new version 812 of the softwareis backwards compatible with the initial version of the software.

At 908 (see FIG. 11B), after the new version 812 of the software isinstalled on the first physical SP 120, the first and second sets ofVSPs 150 are moved from the second physical SP 120 to the first physicalSP 120 to provision the first physical SP 120 to process host I/Orequests concurrently on the first and second sets of host file systemsusing the first and second sets of VSPs 150 (also see FIG. 9). Anyblock-based processing performed by the second physical SP 120 istransferred over to the first physical SP 120 at this time as well.Accordingly, the second physical SP 120 is now free to receive asoftware upgrade.

At 910, after the first and second sets of VSPs 150 are moved from thesecond physical SP 120 to the first physical SP 120 and while the firstphysical SP 120 processes host I/O requests concurrently on the firstand second sets of host file systems using the first and second sets ofVSPs 150, the new version 812 of the software is installed on the secondphysical SP 120 (FIG. 9).

At 912, the second set of VSPs is moved from the first physical SP 120back to the second physical SP 120 to re-provision the second physicalSP 120 to process host I/O requests on the second set of host filesystems using the second set of VSPs 150 (also see FIG. 10). Anyblock-based processing initially performed by the second physical SP 120is transferred back over to the second physical SP 120 at this time aswell.

At 914, after the second set of VSPs 150 is moved from the firstphysical SP 120 back to the second physical SP 120, the physical SPs 120process host I/O requests on the host file systems while the new version812 of the software is installed on the physical SPs 120 (FIG. 10).

At 916, the data storage apparatus 116 receives a command to finish NDU.In particular, the user may enter a commit command 810 into the userinterface 800 which directs the data storage apparatus 116 to switcheach of the first and second physical SPs 120 from operating using thenew version 812 of the software in the backward compatible mode tooperating using the new version 812 of the software in a new versionmode which is different than the backward compatible mode.Alternatively, the user may enter a complete command 810 which directsthe data storage apparatus 116 to deem the NDU process to be completewhile continuing to operate each of the first and second physical SPs120 using the new version 812 of the software in the backward compatiblemode.

As described above, improved techniques are directed to performing NDUof software on a data storage apparatus 116 having multiple physical SPs120 which access VSPs 150. The VSPs 150 are capable of being moved fromone physical SP 120 to another during NDU. Accordingly, a new version812 of software can be installed on each physical SP 120 while thatphysical SP 120 is free of VSPs 150, i.e., with the VSPs 150 residing onone or more remaining physical SPs 120 of the data storage apparatus116. Additionally, the new version 812 of the software is capable ofbeing backwards compatible so that once all of the physical SPs 120 havethe new version installed, a coordinated switchover can take place whichcommits the data storage apparatus 116 to operating in accordance with anew mode that is different from the backwards compatible mode.

While various embodiments of the present disclosure have beenparticularly shown and described, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present disclosure asdefined by the appended claims.

For example, it should be understood that the data storage apparatus 116was described above as having two physical SPs 120 by way of exampleonly. In other arrangements, the data storage apparatus 116 has morethan two physical SPs 120 (e.g., three, four, six, eight, and so on). Inthese arrangements, the processing of host I/O requests is moved fromeach physical SP 120 and then the software on that physical SP 120 isupgraded. In some arrangements, movement of such processing is performedin a smart load balancing manner for improved quality of service.Accordingly, the data storage apparatus 116 is able to carry out NDUsince processing of host I/O requests, including VSP access, whichenables processing of file-based I/Os, is now movable among physical SPs120. That is, since the abstraction provided by VSPs 150 which containentire file system personalities makes file-based processing movable(and there may be many VSP instances on each physical SP 120), NDU ispossible.

Further, although features are shown and described with reference toparticular embodiments hereof, such features may be included in any ofthe disclosed embodiments and their variants. Thus, it is understoodthat features disclosed in connection with any embodiment can beincluded as variants of any other embodiment, whether such inclusion ismade explicit herein or not. Those skilled in the art will thereforeunderstand that various changes in form and detail may be made to theembodiments disclosed herein without departing from the scope of thedisclosure. Such modifications and enhancements are intended to belongto various embodiments of the disclosure.

What is claimed is:
 1. A method of performing a non-disruptive upgradeof software installed on physical storage processors of a data storageapparatus, the method comprising: with (i) a first physical storageprocessor initially using a first set of virtual storage processors(VSPs) to define a first set of operating environments for a first setof host file systems, (ii) a second physical storage processor initiallyusing a second set of VSPs to define a second set of operatingenvironments for a second set of host file systems, wherein each one ofthe host file systems in the first and second sets of host file systemsis contained within one of a plurality of lower-deck files of alower-deck file system of the data storage apparatus, and (iii) aninitial version of the software being installed on each of the first andsecond physical storage processors, processing host input/output (I/O)requests on the host file systems by the physical storage processors;moving the first set of VSPs from the first physical storage processorto the second physical storage processor to provision the secondphysical storage processor to process host I/O requests concurrently onthe first and second sets of host file systems using the first andsecond sets of VSPs; after the first set of VSPs is moved from the firstphysical storage processor to the second physical storage processor andwhile the second physical storage processor processes host I/O requestsconcurrently on the first and second sets of host file systems using thefirst and second sets of VSPs, installing a new version of the softwareon the first physical storage processor, the new version of the softwarebeing backwards compatible with the initial version of the software; andconverting, by the second physical storage processor, after the firstset of VSPs is moved from the first physical storage processor to thesecond physical storage processor, the host I/O requests on the firstand second sets of host file systems into reads and writes to thelower-deck files containing each of the host file systems in the firstand second sets of host files systems.
 2. A method as in claim 1,further comprising: after the new version of the software is installedon the first physical storage processor, moving the first and secondsets of VSPs from the second physical storage processor to the firstphysical storage processor to provision the first physical storageprocessor to process host I/O requests concurrently on the first andsecond sets of host file systems using the first and second sets ofVSPs; and after the first and second sets of VSPs are moved from thesecond physical storage processor to the first physical storageprocessor and while the first physical storage processor processes hostI/O requests concurrently on the first and second sets of host filesystems using the first and second sets of VSPs, installing the newversion of the software on the second physical storage processor.
 3. Amethod as in claim 2, further comprising: moving the second set of VSPsfrom the first physical storage processor back to the second physicalstorage processor to re-provision the second physical storage processorto process host I/O requests on the second set of host file systemsusing the second set of VSPs; and after the second set of VSPs is movedfrom the first physical storage processor back to the second physicalstorage processor, processing host I/O requests on the host file systemsby the physical storage processors using the new version of the softwareinstalled on the physical storage processors.
 4. A method as in claim 3wherein processing host I/O requests on the host file systems by thephysical storage processors while the new version of the software isinstalled on the physical storage processors includes: processing hostI/O requests on the host file systems by the physical storage processorswhile each of the first and second physical storage processors operatesusing the new version of the software in a backward compatible mode. 5.A method as in claim 4, further comprising: receiving a commit command,and in response to the commit command, switching each of the first andsecond physical storage processors from operating using the new versionof the software in the backward compatible mode to operating using thenew version of the software in a new version mode which is differentthan the backward compatible mode.
 6. A method as in claim 5 whereinoperating the first and second physical storage processors using the newversion of the software in the backward compatible mode includesprocessing host I/O requests in accordance with a first file-basedprotocol; and wherein operating the first and second physical storageprocessors using the new version of the software in the new version modeincludes processing host I/O requests in accordance with a secondfile-based protocol that is different than the first file-basedprotocol.
 7. A method as in claim 4, further comprising: receiving acompletion command, and in response to the completion command, deemingthe non-disruptive upgrade of the software to be complete whilecontinuing to operate each of the first and second physical storageprocessors using the new version of the software in the backwardcompatible mode rather than switch to using the new version of thesoftware in a new version mode which is different than the backwardcompatible mode.
 8. A method as in claim 4 wherein each VSP includes aroot file system and a VSP configuration file system contained within aset of lower-deck files of the lower-deck file system of the datastorage apparatus, the VSP configuration file system storing VSP datawhich identifies host file system operating environment characteristics;wherein using the first set of VSPs to define the first set of operatingenvironments includes accessing the VSP configuration file system ofeach VSP of the first set; and wherein using the second set of VSPs todefine the second set of operating environments includes accessing theVSP configuration file system of each VSP of the second set.
 9. A methodas in claim 4 wherein the data storage apparatus includes at least twophysical storage processors; and wherein the method further comprises:prior to processing the host I/O requests on the host file systems bythe physical storage processors, updating a configuration database toidentify, for each VSP, one of the physical storage processors as aprimary owner of that VSP, each VSP residing on its primary owner uponcompletion of the non-disruptive upgrade.
 10. A method as in claim 4,further comprising: trespassing block-based processing among thephysical storage processors in tandem with moving VSPs among thephysical storage processors to remove processing of all host I/Orequests from each physical storage processor when the new version ofthe software is installed on that physical storage processor.
 11. Amethod as in claim 1, wherein each VSP stores its own network address;wherein each host I/O request is directed to a network address of a VSP;and wherein moving the first set of VSPs from the first physical storageprocessor to the second physical storage processor is performed withoutchanging the network address of any VSP in the first set of VSPs.
 12. Acomputer program product having a non-transitory computer readablemedium which stores a set of instructions to perform a non-disruptiveupgrade of software installed on physical storage processors of a datastorage apparatus, the set of instructions, when carried out byprocessing circuitry, causing the processing circuitry to perform amethod of: with (i) a first physical storage processor initially using afirst set of virtual storage processors (VSPs) to define a first set ofoperating environments for a first set of host file systems, (ii) asecond physical storage processor initially using a second set of VSPsto define a second set of operating environments for a second set ofhost file systems, wherein each one of the host file systems in thefirst and second sets of host file systems is contained within one of aplurality of lower-deck files of a lower-deck file system of the datastorage apparatus, and (iii) an initial version of the software beinginstalled on each of the first and second physical storage processors,processing host input/output (I/O) requests on the host file systems bythe physical storage processors; moving the first set of VSPs from thefirst physical storage processor to the second physical storageprocessor to provision the second physical storage processor to processhost I/O requests concurrently on the first and second sets of host filesystems using the first and second sets of VSPs; after the first set ofVSPs is moved from the first physical storage processor to the secondphysical storage processor and while the second physical storageprocessor processes host I/O requests concurrently on the first andsecond sets of host file systems using the first and second sets ofVSPs, installing a new version of the software on the first physicalstorage processor, the new version of the software being backwardscompatible with the initial version of the software; and converting, bythe second physical storage processor, after the first set of VSPs ismoved from the first physical storage processor to the second physicalstorage processor, the host I/O requests on the first and second sets ofhost file systems into reads and writes to the lower-deck filescontaining each of the host file systems in the first and second sets ofhost files systems.
 13. A computer program product as in claim 12wherein the method further comprises: after the new version of thesoftware is installed on the first physical storage processor, movingthe first and second sets of VSPs from the second physical storageprocessor to the first physical storage processor to provision the firstphysical storage processor to process host I/O requests concurrently onthe first and second sets of host file systems using the first andsecond sets of VSPs; and after the first and second sets of VSPs aremoved from the second physical storage processor to the first physicalstorage processor and while the first physical storage processorprocesses host I/O requests concurrently on the first and second sets ofhost file systems using the first and second sets of VSPs, installingthe new version of the software on the second physical storageprocessor.
 14. A computer program product as in claim 13 wherein themethod further comprises: moving the second set of VSPs from the firstphysical storage processor back to the second physical storage processorto re-provision the second physical storage processor to process hostI/O requests on the second set of host file systems using the second setof VSPs; and after the second set of VSPs is moved from the firstphysical storage processor back to the second physical storageprocessor, processing host I/O requests on the host file systems by thephysical storage processors using the new version of the softwareinstalled on the physical storage processors.
 15. A computer programproduct as in claim 14 wherein processing host I/O requests on the hostfile systems by the physical storage processors while the new version ofthe software is installed on the physical storage processors includes:processing host I/O requests on the host file systems by the physicalstorage processors while each of the first and second physical storageprocessors operates using the new version of the software in a backwardcompatible mode.
 16. A computer program product as in claim 15 whereinthe method further comprises: trespassing block-based processing amongthe physical storage processors in tandem with moving VSPs among thephysical storage processors to remove processing of all host I/Orequests from each physical storage processor when the new version ofthe software is installed on that physical storage processor.
 17. Amethod as in claim 8 wherein each VSP includes a namespace independentof the namespace of any other VSP; and wherein the root file system andVSP configuration file system of each VSP are both contained within thenamespace of the VSP.
 18. An electronic apparatus, comprising: memory;and control circuitry coupled to the memory, the memory storinginstructions which, when carried out by the control circuitry, cause thecontrol circuitry to perform a non-disruptive upgrade of softwareinstalled on physical storage processors by: with (i) a first physicalstorage processor initially using a first set of virtual storageprocessors (VSPs) to define a first set of operating environments for afirst set of host file systems, (ii) a second physical storage processorinitially using a second set of VSPs to define a second set of operatingenvironments for a second set of host file systems, wherein each one ofthe host file systems in the first and second sets of host file systemsis contained within one of a plurality of lower-deck files of alower-deck file system of the data storage apparatus, and (iii) aninitial version of the software being installed on each of the first andsecond physical storage processors, processing host input/output (I/O)requests on the host file systems by the physical storage processors,moving the first set of VSPs from the first physical storage processorto the second physical storage processor to provision the secondphysical storage processor to process host I/O requests concurrently onthe first and second sets of host file systems using the first andsecond sets of VSPs, after the first set of VSPs is moved from the firstphysical storage processor to the second physical storage processor andwhile the second physical storage processor processes host I/O requestsconcurrently on the first and second sets of host file systems using thefirst and second sets of VSPs, installing a new version of the softwareon the first physical storage processor, the new version of the softwarebeing backwards compatible with the initial version of the software, andconverting, by the second physical storage processor, after the firstset of VSPs is moved from the first physical storage processor to thesecond physical storage processor, the host I/O requests on the firstand second sets of host file systems into reads and writes to thelower-deck files containing each of the host file systems in the firstand second sets of host files systems.
 19. An electronic apparatus as inclaim 18 wherein the instructions further cause the control circuitryto: after the new version of the software is installed on the firstphysical storage processor, move the first and second sets of VSPs fromthe second physical storage processor to the first physical storageprocessor to provision the first physical storage processor to processhost I/O requests concurrently on the first and second sets of host filesystems using the first and second sets of VSPs; and after the first andsecond sets of VSPs are moved from the second physical storage processorto the first physical storage processor and while the first physicalstorage processor processes host I/O requests concurrently on the firstand second sets of host file systems using the first and second sets ofVSPs, install the new version of the software on the second physicalstorage processor.
 20. An electronic apparatus as in claim 19 whereinthe instructions further cause the control circuitry to: move the secondset of VSPs from the first physical storage processor back to the secondphysical storage processor to re-provision the second physical storageprocessor to process host I/O requests on the second set of host filesystems using the second set of VSPs; and after the second set of VSPsis moved from the first physical storage processor back to the secondphysical storage processor, process host I/O requests on the host filesystems by the physical storage processors using the new version of thesoftware installed on the physical storage processors.
 21. An electronicapparatus as in claim 20 wherein processing host I/O requests on thehost file systems by the physical storage processors while the newversion of the software is installed on the physical storage processorsincludes: processing host I/O requests on the host file systems by thephysical storage processors while each of the first and second physicalstorage processors operates using the new version of the software in abackward compatible mode.
 22. An electronic apparatus as in claim 21,further comprising: a configuration database coupled to the controlcircuitry; and wherein the instructions further cause the controlcircuitry to: prior to processing the host I/O requests on the host filesystems by the physical storage processors, update the configurationdatabase to identify, for each VSP, one of the physical storageprocessors as a primary owner of that VSP, each VSP residing on itsprimary owner upon completion of the non-disruptive upgrade.